Packaged hydraulic oil tank assembly and attachment kit

ABSTRACT

A tank assembly stores hydraulic oil in a system for actuating hydraulically operated cylinders, specifically on Class VI, VII and VIII trucks. A pump draws the fluid from the tank to force the hydraulic cylinder to an upright position. When the pump valve is shifted to the down position, the hydraulic fluid is returned to the storage tank at a reduced velocity without the reduction of the rate of flow in gallons per minute below the rated pump capacity, thus preventing the aeration of the fluid. An attachment kit includes grooves in the top of the tank-receiving nylon belts with loops at their ends receiving U-bolts for attaching to flanges of a tray, for mounting on a truck.

BACKGROUND OF THE INVENTION

This invention relates to a tank assembly for storing hydraulic oil in asystem for actuating hydraulically operated cylinders. Morespecifically, this invention comprises a tank assembly for storinghydraulic fluid on Class VI, VII, and VIII trucks as applied in theheavy-duty truck market in the United States. As the hydraulic system isactuated, the pump draws hydraulic fluid from the tank for use inforcing the hydraulic cylinder, mounted under the dump trailer, into anupright position in order to discharge the commodity being transferred.As the pump valve is shifted to the down position, the hydraulic fluidreturns through the system to the tank assembly for storage. Thisreturning fluid must not be allowed to aerate; therefore, the velocityof the returning hydraulic fluid must be reduced without reducing therate of flow in gallons per minute below the rated pump capacity at 1000rpms.

Prior storage systems use both conventional metal and moldedpolyethylene reservoirs as storage components for the hydraulic fluid.Each of these systems have inherent problems troubling to the productuser. Conventional metal reservoirs have welded seams which, dependingon the skill of the welder, can leak or leave a metal slag residue.These contaminants, such as slag, sands, and rust, range in the 100-200micron size. This size contaminant causes problems because high pressurehydraulic components cannot pass particles larger than 10 micronswithout eventual destruction to the system.

Prior molded polyethylene reservoirs have addressed and corrected thecontamination problems inherent in the fabricated metal reservoirs;however, three distinct problems have arisen with the use of the moldedreservoirs: 1) annoying leaks at the junction where the metal portfitting is molded into the polyethylene; 2) tank distortion caused bythe occasional heat build-up in the hydraulic system and consequentlythe hydraulic fluid stored in the reservoir; and 3) inadequatelyproviding for a convenient and effective procedure for diffusinghydraulic fluids as they are returned to the storage reservoir or tank.

SUMMARY OF THE INVENTION

The molded polyethylene tank has proven its ability to reduce, if noteliminate, the possibility of weakened seams or bursting of thereservoir as shown in prior art. It will be apparent from the foregoingthat the object of the present invention is to provide acontaminant-free environment that is resistant to bursting or puncture,resistant to warping or physical distortion, and free from leaks at thepoints of metal port installation.

This pre-packaged tank system will further provide a convenient diffusersystem that may be used in either of the (2) two - 2" National PipeThread Ports the system provides. This diffuser provides convenient 2"N.P.T. male threads for insertion into the 2" N.P.T. female fittingsthat are molded into the tank assembly. The product's user may useeither of the two bottom ports provided for the drawing of or returningof hydraulic fluid to the tank assembly. Diffuser design prevents theaeration of returning hydraulic fluid without reducing the rate of fluidflow in gallons per minute below the rated pump capacity at 1000 rpms.

The present invention also provides the use of metal compression fittingports, designed to be molded into the tank for use as accessory ports.This proprietary design provides additional strength as used in therotation molding process, and when used with the externally mountedthreaded nut will provide a compression seal to prevent any leakage fromthe tank assembly.

Basic to the present invention is the overall design of the molded tank.The rotation molding process, that of rotating the design tool fixturethrough an oven with sufficient heat as to melt the plastic powdermaterial and to form a uniform walled tank assembly, will causedistortion in a tank as a result of normal processing. As the designtool fixtures are cooled upon exiting the oven area, water is applied tocool each part. This results in the exterior skin of the polyethylenetank cooling more rapidly than the inside wall. This results in a "shortskin" or more shrinkage on the outside than on the inside wall. Thisphenomenon results in a natural tendency for the tank to bow-in,especially if the unit is exposed to recurring occasional heat in the120°-145° range--such as is seen in the tank system application. Thepresent invention addresses this problem by maintaining areas withminimum flat surface area. Strapping guides are, in reality, designed tobreak up the flat surface area, and are recessed to providereinforcement of the tank. The larger surface areas have been designedwith a crown in the material, again to control the normal tendencies ofthe material resulting from the manufacturing process. It is importantto the industry that this tank assembly provide for 50-55 galloncapacity; consequently, the dimensioning of this tank assembly isextremely important in providing the volume required by the industry andin providing a polyethylene tank that will retain its original shape anddesign to be aesthetically pleasing, as well as functional, for the enduser.

Additionally, the tank system is known as an open system--or one thatdraws and displaces air as hydraulic fluid is drawn from or returned tothe tank. The present invention provides a filler/breather assembly, aswell as a bayonet-style, 40 micron breather cap. The filler/breatherassembly consists of a nylon screen assembly extending 4" down into thetank through the filler port. This assembly allows more air to bedisplaced than previous art. The assembly also acts as a buffer to breakup the movement of hydraulic fluid and prevent material from "sloshing"out of the fill cap.

All parts and assemblies described herein are shipped in kit form,complete in one 200# test weight corrugated carton, which has thefollowing dimensions: 411/8" long, 161/8" wide, and 271/8" high.

These and further and other objects and features of the invention areapparent in the disclosure, which includes the above and ongoing writtenspecification, with, the claims and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the present invention and providesa perspective view of "THE AMERICAN WET TANK SYSTEM" and the parts thatmake up the completed kit.

FIG. 2 is an illustration of the present invention installed on avehicle chassis with "Tank System" located rearward of the cab.

FIGS. 3A, 3B, 3C and 3D are respectively schematic illustrations of sideand end views of a tank and top and side views of a mount boss of apolyethylene tank assembly indicating tank design, detail on fill portmounting boss, diffuser placement, and compression fitting portlocations.

FIGS. 4A, 4B and 4C are top, side and end views of a tank mounting base,and

FIGS. 4D and 4E are front and side views of four chassis mountingangles.

FIG. 5 is a schematic illustration of tank mounting straps--two requiredper assembly.

FIGS. 6A and 6B are schematic side and end views of a diffuserassembly--one required per assembly.

FIGS. 7A and 7B are a side cross-section and top view of compressionport fittings--two required per assembly and

FIGS. 7C and 7D are a side cross-section and top view of a compressionnut for threading on the compression port fitting.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 discloses the "AMERICAN WET TANK SYSTEM" component parts asrequired for shipment of the complete kit. Shown is the tank assembly 10of the present invention which is mounted to the base 20 by means ofstrap assembly 30. Tank assembly is mounted to truck chassis by means ofa mounting kit 50, which includes four mounting angles 56, four rubbermounting pads 52, bolted as shown with four bolts 54 which extendthrough holes 53 in carriage base 20, four washers 53, four nyloc nuts55 and four 115# compression springs 51.

FIG. 2 discloses the tank assembly 10 of the present invention installedon a truck 12 as the storage component of a hydraulic system forsupplying fluid under pressure to hydraulically actuated devices, suchas a dump body (not shown) mounted on the rear portion of truck frame14. The hydraulic system may also be used to supply fluid under pressureto additional fluid operated equipment associated with the vehicle, suchas hoists, winches, lifts, etc.

Power for the hydraulic system is supplied by a power take-off unit 16which is driven by the truck power train, not shown. A driven outputshaft 16 transfers power from the power take-off unit 16 to the inputshaft 28 of hydraulic pump 28. Hydraulic fluid is conveyed underpressure from pump 28 through conduit 26 to the dump body actuatingmechanism, or to other hydraulically operated equipment associated withtruck 12.

Hydraulic fluid for use in the above-described system is stored in tankassembly (FIG. 1), which comprises a tank 10 with crowning 5 on bothsides between indentations 9 mounted by means of a platform 20 to thetruck frame 14. Straps 30 extend in indentations 9 around the peripheryof tank 10 and fasten the tank assembly 10 to platform 20 with U-bolts31 which extend through holes 21 and which are secured with nuts 32(FIG. 1). A breather cap 42 of filler breather assembly 40 is providedon top of the tank 10 to prevent build up of pressure inside the tank.Filler breather assembly 40 has a four inch long nylon mesh basket 41and a 40 micron filter bayonet cap 42 attached to a fill opening 43 inthe tank by six screws 44 corresponding to the brass inserts 45 moldedin the polyethylene material. Dual port openings 8 with metallic portfittings 11, forming leakproof compression seals 7 (FIG. 3) are providedin the bottom of the tank. In building a standard two-line system, oneport is sealed with a 2" N.P.T. plug. A diffuser unit 60 (FIG. 6) isscrewed into remaining port 11 with conduit 36 screwed into the 11/4"N.P.T. port in the bottom of the diffuser.

Actual arrangement of plumbing is determined by the installer. Tankallows single line installation for drawing and returning hydraulicfluid to tank or the use of two ports, one to draw fluid into systemwith second line plumbed to second port for hydraulic fluid returning tothe tank. The present invention allows for more flexibility in systemdesign for the installer/user.

The opposite end of conduit 36 is connected to pump 28. Pump 28 isadapted to pump hydraulic fluid stored in the tank 10 through port 11(FIG. 3) and conduit 36 and thence through conduit 26 to thehydraulically operated equipment associated with truck 12. Assuming suchequipment comprises a conventional dump body, hydraulic fluid passingfrom pump 28 to conduit 26 will function to raise the dump body to aninclined position relative to the truck frame 14. When it is desired tolower the dump body from a raised position, the valve on pump 28 isplaced in the "lower" position allowing the weight of the dump body toforce the hydraulic fluid back through conduit 26, pump 28 and conduit36 to tank assembly 10.

Industry standards also call for the installation of what is commonlycalled a "three line system". This would require use of both bottom tankports 11 (FIG. 3). Diffuser 60 (FIG. 6) would be installed in one of thebottom metal ports 11 (FIG. 3). Conduit 36 would be installed inopposite tank port fitting 11 and connected to pump as described above.A third line (not shown) is run from the dump body hydraulic cylinder tothe second tank port fitting 11 to complete the system. Either system isacceptable; however, the three line system continually cycles the systemand results in less heat being produced.

FIGS. 3, 4, 5, 6 and 7 disclose the specific design of the polyethylenetank and the components that make up the "American Wet Tank System".FIG. 3 indicates the position and size of the metal port fittings 70(FIG. 7) which are molded into the bottom of tank 10 (FIG. 1).Compression nuts (2 required) 71 (FIG. 7) screw on the portion of thefittings extending out the bottom of the tank. These nuts 71 (FIG. 7)are torqued to a pressure resulting in the compression of thepolyethylene material between the nut and the molded fitting. Thisresults in a strong, leak proof fitting. Dimensions of the tank (FIG. 3)indicate the reinforcing strap guides, radius corners, and the largestsurfaced areas crowned, as reinforcement against distortion from theoccasional heat build up as hereinbefore described. This design and itsresulting dimensions create the optimum size tank to meet industrystandards for storing hydraulic fluid for mobile power applications inthe heavy duty truck market.

FIG. 6 discloses the design and specific dimensions of thefilter/diffuser 60. Use of this diffuser 62 prevents returning hydraulicfluid from aerating as it returns to the tank. Perforations 64 shownresult in allowing the velocity of returning fluid to be reduced withoutreducing the rate of flow in gallons per minute below the rated pumpcapacity at 1000 rpms. This filter/diffuser is designed with threads 66for standard National Pipe Thread openings and conveniently fits eitherof the tank port openings 11 (FIG. 3). Diffuser/filter system isinserted into the tank port from the outside and screwed into placeusing standard pipe dope material to provide leak proof seals.

As previously stated, the rotation molded polyethylene tank provides acontaminant-free environment, is uniform in thickness and seamless. Thepolyethylene tank is tough, rigid, lightweight, abrasion resistant andcorrosion-free. The design, as described, eliminates the distortion andwarping problems presently encountered by polyethylene tanks used in themobile power application in the heavy duty truck market.

Bottom tank port fittings, as described, eliminate the possibility ofleaks as experienced by users of the present art. Fittings furtherprovide added strength to port area, flexibility in system design, and aconvenient method of installing filter/diffuser unit, as well as conduitattachment.

The filter/diffuser assembly offers the installer/user the option ofutilizing either port as a return line and the convenience of N.P.T.ports, simply sealed with the use of a standard pipe dope material.

The entire "wet tank assembly" is conveniently packaged and shipped tothe installer/user in a single carton.

The foregoing embodiment is exemplary of the invention and the prototypeunit now developed; however, any variation adopted may be made withoutdeparting from the spirit and scope of the invention as defined in thefollowing claims.

I claim:
 1. A tank assembly comprising a rotationally moldedpolyethylene material tank, comprising a rectangular shape, furthercomprising indentations in the tank for reinforcing the tank againstdistortion and for guiding alignment guides, a carriage base adjacentthe tank, retaining straps in the guides for attachment of the tank tothe carriage base, U-bolt attachments at ends of the retaining strapsand extending through holes in the carriage base; further comprising twoport openings having two metallic port fittings molded into thepolyethylene material of the tank for forming a component part of leakproof compression seals; further comprising a filler/breather assemblyat a top of the tank; further comprising a filter/diffuser connected toone of the port fittings for retarding returning fluid velocity withoutreducing flow in gallons per minute; further comprising a chassisattachment kit connected to the carriage base for mounting the carriagebase and the tank assembly, further providing a crowning of both sidesof the tank between the indentations for providing reinforcement and forresisting distortion caused by occasional heat build up; furtherproviding, for attachment to the two metallic port fittings molded inthe polyethylene material, two externally attached compression nuts toprovide said leak proof compression seals; the two port fittings and thenuts being adaptable for an installer/user plumbing arrangement and toallow external installation and sealing of said filter/diffuser ineither port opening.
 2. The apparatus of claim 1, the filler breatherassembly further comprising a filler/breather assembly of a four inchlong nylon mesh basket, a 40 micron filter bayonet cap attached to afill opening in the tank by means of six screws corresponding to brassinserts molded into the polyethylene material.
 3. A wet tank assemblysuitable for packaging and transportation and resistance to distortion,comprising a tank having dual screw-in ports; an externally mounted,screw-in filter/diffuser connected to one of the ports, afiller/breather assembly connected to the tank for providing passage ofair into and out of the tank; attachment straps, circumferentialindentations on the tank for providing reinforcement, as well as forserving to guide the attachment straps, corresponding U-bolts attachedto ends of the straps, a carriage base, through holes provided in thecarriage base for receiving the U-bolts; further comprising a chassisattachment kit consisting of four pre-punched mounting angles, fourmounting pads, four cap screws, four lock nuts, four compressionsprings; all prepackaged into a single shipping carton, which consistsof one corrugated carton; this complete tank assembly with correspondingcarton providing shipment of complete product by parcel service; furtherthe tank assembly dimensions do not exceed 130" girth and length.
 4. Thewet tank assembly of claim 3, wherein the four mounting pads have a 70durometer.
 5. The wet tank assembly of claim 3, wherein the fourcompression springs are 115# springs.
 6. The wet tank assembly of claim3, wherein dimensions of the shipping carton are about 411/8" long by161/2" wide by 271/8" high.
 7. The wet tank assembly of claim 3, whereinthe shipping carton is a 200 pound test weight carton.
 8. The wet tankassembly of claim 3, wherein the entire assembly and carton weighs lessthan 70 pounds.